Level of protection

​​​​​​​​We can define ‘level of protection’ as the degree of protection afforded to a water body based on its ecosystem condition (current or desired health status of an ecosystem relative to the degree of human disturbance).

The level of protection informs the acceptable water/sediment quality for a waterway.

In the Water Quality Guidelines, level of protection only applies to aquatic ecosystems. But it could be applied to other community values.

We select a level of protection to:

  • maintain the existing ecosystem condition, or
  • enhance a modified ecosystem by targeting the most appropriate level of condition.

You would typically decide on a level of protection for a region through a process of stakeholder involvement, by determining community values and associated management goals in the context of current ecosystem condition and the community’s long-term desires for the ecosystem. This occurs at at Step 2 of the Water Quality Management Framework.

Check with relevant local authorities in your jurisdiction who might already have established levels of protection, and possibly different categories to consider.

Ecosystem conditions and associated level of protection

We recognise 3 categories of current or desired ecosystem condition in the Water Quality Guidelines. You can specify a corresponding level of protection by using these ecosystem condition categories:

  • high conservation or ecological value systems
  • slightly to moderately disturbed systems
  • highly disturbed systems.

For each category of ecosystem condition, the Water Quality Guidelines provide specific guidance for:

  • field biological assessments undertaken in waterways
  • applications of appropriate guideline values for physical and chemical stressors, including toxicants
  • attributes and corresponding levels of protection.
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High conservation or ecological value systems

Attributes

Effectively unmodified or other highly valued ecosystems, typically (but not always) occurring in national parks and conservation reserves, or in remote and inaccessible locations.

While there are no aquatic ecosystems in Australia and New Zealand entirely without some human influence, the ecological integrity of our high conservation or ecological value systems is regarded as ‘intact’.

Level of protection

For ecosystems highly valued for their unmodified state and outstanding natural and conservation values, there should typically be no change in biodiversity beyond natural variability. Where possible, there should also be no change in water/sediment chemical and physical properties, including toxicants.

You should only relax the chemical and physical guideline values for these ecosystems if it is known that such a degradation in water/sediment quality will not compromise the objective to maintain biological diversity in the system.

Consider management action for any apparent trend away from a baseline, or once an agreed threshold has been reached.

Appropriate level of protection for indicator types

Biological indicators (field)
  • No change in biodiversity beyond natural variability. We recommend ecologically conservative decision criteria for level of detection.
  • Where reference condition is poorly characterised, we recommend actions to increase the power of detecting a change.
  • Take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.
Physical and chemical stressors
  • We recommend no change beyond natural variability, using ecologically conservative decision criteria for detecting change.
  • Where reference condition is poorly characterised, we recommend actions to increase the power of detecting a change.
  • Any relaxation of this objective should only be considered where comprehensive biological effects and monitoring data clearly show that biodiversity would not be altered.
  • Take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.
Toxicants
  • For naturally occurring toxicants, do not exceed background concentrations.
  • Where local biological or chemical data have not yet been gathered, apply 99% species protection default guideline values (DGVs) if they exist.
  • Any relaxation of these objectives should only be considered where comprehensive biological effects and monitoring data clearly show that biodiversity would not be altered.
    • For toxicants generated by human activities, detection at any concentration could be grounds for investigating their source and for management intervention. For globally distributed chemicals, such as residues of DDT (dichlorodiphenyltrichloroethane), it may be necessary to apply representative background concentrations — as for naturally occurring toxicants.
    • In the case of effluent discharges, direct toxicity assessment (DTA) should be required.
  • Take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.

Slightly to moderately disturbed systems

Attributes

Ecosystems in which aquatic biological diversity may have been adversely affected to a relatively small but measurable degree by human activity. The biological communities remain in a healthy condition and ecosystem integrity is largely retained.

Freshwater systems would typically have slightly to moderately cleared catchments or reasonably intact riparian vegetation. For example, rural streams receiving runoff from land disturbed to varying degrees by grazing or pastoralism.

Marine systems would typically have largely intact habitats and associated biological communities. For example, marine ecosystems lying immediately adjacent to metropolitan areas.

Level of protection

For slightly to moderately disturbed ecosystems, some relaxation of the stringent management approach used for unmodified ecosystems may be appropriate. An increased level of change might be acceptable, or there might be reduced inferential strength for detecting any change in biological diversity.

Nevertheless, maintenance of biological diversity relative to a suitable reference condition should be a key management goal.

For physical and chemical (PC) stressors (including toxicants) in water and sediment, the default guideline values (DGVs) ​provide a suitable level of protection for slightly to moderately disturbed ecosystems.

Appropriate level of protection for indicators types

Biological indicators (field)
  • Negotiated statistical decision criteria for detecting departure from reference condition. Maintenance of biodiversity is still a key management goal.
  • Where reference condition is poorly characterised, suggest actions to increase the inferential strength of the monitoring program.
  • You may need to take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.
Physical and chemical stressors
  • Always preferable to use data on local biological effects to derive guideline values.
  • If local biological effects data are unavailable, use local or regional reference site data to derive guideline values using our suggested approach. Alternatives to the default decision criteria for detecting departure from reference condition may be negotiated by stakeholders but should be ecologically conservative and not compromise biodiversity.
  • Where local reference site data are not yet gathered, apply regional DGVs.
  • You may need to take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.
Toxicants
  • Always preferable to use data on local biological effects, including direct toxicity assessment (DTA), to derive site-specific guideline values.
  • For toxicants in water, apply 95% species protection DGVs, or 99% species protection for highly bioaccumulating toxicants, if local biological-effects data are unavailable.
  • For toxicants in sediment, use our toxicant DGVs for sediment quality.
  • In the case of effluent discharges, DTA may be required.
  • You may need to take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.

Highly disturbed systems

Attributes

Measurably degraded ecosystems of lower ecological value. For example, shipping ports and sections of harbours serving coastal cities, urban streams receiving road and stormwater runoff, or rural streams receiving runoff from intensive horticulture.

Level of protection

The philosophy applied to degraded aquatic ecosystems is that they still retain — or after rehabilitation may have — ecological or conservation values but for practical reasons it may not be feasible to return them to a slightly to moderately disturbed condition. At least in the short to medium term.

Water quality management for highly disturbed ecosystems can be more flexible.

You might aim to retain a functional yet modified ecosystem that would support the assigned management goals.

In most cases, the ecological values of highly disturbed ecosystems can be maintained by applying our default guideline values (DGVs). But there could be situations where the DGVs would be too stringent and a lower level of protection would be sought.

​We provide some guidance to assist managers in these situations in the discussion of each type of indicator.

Highly disturbed systems should not be regarded as ‘pollution havens’. The concepts of adaptive ma​nagement and continual improvement should always be promoted, to maximise future options for a waterway.

Level of protection for indicator types

Biological indicators (field)
  • Select reference condition within this category based on community desires. Negotiated statistical decision criteria for detecting departure from reference condition may be more lenient than the other 2 categories of ecosystem condition.
Physical and chemical stressors
  • Use local or regional reference site data toderive guideline values using our suggested approach. Select reference condition within this category based on community desires. Negotiated statistical decision criteria may be more lenient than the other 2 categories of ecosystem condition.
  • Where local reference site data are not yet gathered, apply regional DGVs, or use biological effects data from the literature to derive guideline values.
Toxicants
  • Apply the same DGVs as for slightly to moderately disturbed systems.
  • Lower protection levels may be accepted by stakeholders if water quality for slightly to moderately disturbed systems cannot yet be met:
  • For toxicants in water, 90% or 80% species protection DGVs may be acceptable.
  • For toxicants in sediment, a relaxation of the DGVs may be acceptable, taking into account both the DGVs and upper values (GV-high). Direct toxicity assessment (DTA) could be used as an alternative approach to deriving site-specific guideline values.
  • You may need to take a precautionary approach for assessment of post-baseline data through trend analysis or feedback triggers.

Other approaches to determining a level of protection

Our 3 simple categories of ecosystem condition and associated levels of protection form a subjective approach to viewing the continuum of disturbance across ecosystems.

Stakeholders in different jurisdictions, catchments or regions will inevitably make different judgements about current or desired ecosystem conditions.

For example, in Queensland and Western Australia​, 4 ecosystem conditions are articulated. An ecosystem regarded as highly disturbed in one area could be regarded as only slightly to moderately disturbed in a more populated region.

This is why setting levels of protection must be carried out in an open and transparent way, involving all key stakeholders, to achieve a fair and reasonable agreed outcome.

Local jurisdictions may negotiate alternative site-specific levels of protection after considering many factors, such as:

  • whether a policy of ‘no release’ (total containment) of contaminants applies
  • nature of contaminants that might reach aquatic ecosystems
  • perceived conservation or ecological values of the system, additional to those recognised in our suggested classification of ecosystem condition.

For example, greater consideration might be given to those ecosystems receiving contaminants or effluents of potentially high toxicity that are persistent in the environment (e.g. metals).

Or differing levels of protection could apply according to the anticipated capacity of an ecosystem to readily recover from impact if contamination is to be of short duration.

Reviewing levels of protection

If a system categorised as a particular ecosystem condition is assigned a certain level of protection, it does not have to remain ‘locked’ at that level in perpetuity.

The community values and management goals (including the level of protection) for a particular ecosystem should normally be reviewed after a period of time, and stakeholders may agree to subsequently adopt a different level of protection.

The concepts of adaptive management and continual improvement should always be promoted, to maximise future options for a waterway.

See also: